The conservative former Pennsylvania senator takes 36 percent of the vote to the former Massachusetts governor’s 29 percent. Former House speaker Newt Gingrich follows with 20 percent; Texas Rep. Ron Paul is a distant fourth with 9 percent.

Santorum’s lead here follows a pattern — he does well in Midwestern states with large blue-collar populations, while Romney does better in the West and Northeast.

Ohio will be the major battleground on March 6’s “Super Tuesday,” when 10 states hold their primaries.

Some of the state’s 66 delegates are allocated proportionally, so every candidate will have reason to compete. Early voting has already begun, so there’s an incentive to start campaigning. It will be competitive: 50 percent of the likely Republican voters who were surveyed were open to changing their minds.